Hoses formed of synthetic plastic materials have become commonplace due to advantages in being relatively lightweight, having a wide range of selectable characteristics and being relatively easy to manufacture. One of the difficulties encountered, however, in some of these hose constructions is the incompatibility between materials, selected, for example, for strength in reinforcement purposes and for inertness in providing a jacket or cover for the hose which has a high resistance to external influences. A bond between the cover of the hose and the reinforcement may be desired in order to integrate the hose structure, to improve its kink resistance and its coupling capability and even to improve the external appearance of same. This latter factor is of significance, since with the relatively thin covers which often are employed in these hose constructions, a certain degree of sagging of the cover occurs on bending or flexure of the hose unless a secured arrangement is provided.
In the past it has been typical to secure a bond between the reinforcement and cover by the introduction of a solvent, adhesive or other bonding agent, either to act upon the surface of the reinforcement or the cover to achieve a chemical fusion therebetween. One example of such method is disclosed in U.S. Pat. No. 4,007,070. However, it will be apparent that such method introduces additional steps in the manufacturing process and produces at the very least a localized chemical effect upon the hose structure which may be detrimental to various of the components thereof.
A better method for achieving a bond between reinforcement and cover is disclosed in U.S. Pat. No. 3,633,629 wherein it is taught that a material can be introduced into the reinforcement as one of the components thereof which is compatible in chemical characteristics with the cover so that a fusion bond may be effected therebetween. In this method the compatible thermoplastic material is introduced as one of the yarns forming the braid wrapped under tension onto the core of the structure which is then passed through a suitable pre-heater for raising the temperature thereof just prior to the extrusion of a cover of compatible material thereover. The instant invention is an improvement on such teaching wherein a more desirable hose construction is obtained and a preferred method of construction is provided.